Method and apparatus for continuous monitoring of quality and moisture parameters of liquids

This application relates to a method and a system for determining aging of a liquid. The method includes steps for measuring a relative water content (rS1) of the liquid in a first measurement step at a first temperature (T1), measuring the relative water content (rS2) at a second temperature (T2) in a second measurement step, the first and second measurement step are performed such that absolute water content (w) stays essentially unchanged between these two measurements, and based on these at least two measurement values (rS1, T1, rS2, T2), determining a first water in oil solubility coefficient (B) for the liquid. In accordance with the invention the first water in oil solubility coefficient (B) is monitored essentially continuously in order to determine the liquid quality.